electric polarization, slight relative shift of positive and negative electric charge in opposite directions within an insulator, or dielectric, induced by an external electric field. Polarization occurs when an electric field distorts the negative cloud of electrons around positive atomic nuclei

chemical bonding: Promotion of electrons: Valence bond theory runs into an apparent difficulty with CH4. The valence-shell electron configuration of carbon is 2s22px12py1, which suggests that it can form only two bonds to hydrogen atoms, in which case carbon would have a

electron scattering, deflection of the path of electrons as they pass through a solid (typically a metal, semiconductor, or insulator). Deflections, or collisions, are caused by electrostatic forces operating between the negatively charged electrons and atoms within the solid (see quantum

electron shell, regions surrounding the atomic nucleus containing a specific number of electrons. Each allowed electron orbit is assigned a quantum number n that runs from 1 (for the orbit closest to the nucleus) to infinity (for orbits very far from the nucleus). All the orbitals that have the

electron spectroscopy, method of determining the energy with which electrons are bound in chemical species by measuring the kinetic energies of the electrons emitted upon bombardment of the species with X-ray or ultraviolet radiation. Details of the structure may be inferred from the results

surface analysis: X-ray photoelectron spectroscopy: Since the binding energies of the electrons emitted through XPS are discrete and atoms of different elements have different characteristic electron-binding energies, the emitted electron beam can provide a simple method of elemental analysis. The specificity of XPS is very good, since…

chemical bonding: Lithium through neon: … (Z = 3), one more electron is added. However, that electron cannot occupy the 1s orbital, for it has a property known as spin, which is fundamental to its behaviour. Spin is an intrinsic property of an electron, like its mass or charge. In elementary treatments, spin is often visualized…

chemical analysis: Microwave absorptiometry: …for nuclear magnetic resonance spectrometry, electron spin resonance spectrometry is used to study spinning electrons. The absorbed radiation falls in the microwave spectral region and induces transitions in the spin states of the electrons. An externally applied magnetic field is required. The technique is effective for studying structures and reactions…

particle accelerator: Electron storage rings: Many storage rings have been constructed to study the interactions of electrons with positrons. The principal centres of this research are Cornell University; Stanford University; CERN; Tsukuba, Japan; Frascati, Italy; Beijing, China; and Novosibirsk, Russia.

electronic configuration, the arrangement of electrons in orbitals around an atomic nucleus. The electronic configuration of an atom in the quantum-mechanical model is stated by listing the occupied orbitals, in order of filling, with the number of electrons in each orbital indicated by

electron synchrotron, type of synchrotron designed to accelerate electrons to high energies (see

bacteria: Nutritional requirements: …is generated by means of electron-transfer reactions, in which electrons move from an organic or inorganic donor molecule to an acceptor molecule via a pathway that conserves the energy released during the transfer of electrons by trapping it in a form that the cell can use for its chemical or…

bacteria: Heterotrophic metabolism: …to oxygen using the electron transport chain, a system of enzymes and cofactors located in the cell membrane and arranged so that the passage of electrons down the chain is coupled with the movement of protons (hydrogen ions) across the membrane and out of the cell. Electron transport induces the…

bacteria: Heterotrophic metabolism: …to oxygen using the electron transport chain, a system of enzymes and cofactors located in the cell membrane and arranged so that the passage of electrons down the chain is coupled with the movement of protons (hydrogen ions) across the membrane and out of the cell. Electron transport induces the…

mitochondrion: …produce various components of the electron transport chain (ETC). In many organisms, the mitochondrial genome is inherited maternally. This is because the mother’s egg cell donates the majority of cytoplasm to the embryo, and mitochondria inherited from the father’s sperm are usually destroyed.

phosphorescence: …called a metastable level, or electron trap, because a transition between the metastable level and other levels is forbidden (highly improbable). Once an electron has fallen from the excited level to the metastable level (by radiation or by energy transfer to the system), it remains there until it makes a…

electron tube, device usually consisting of a sealed glass or metal-ceramic enclosure that is used in electronic circuitry to control a flow of electrons. Among the common applications of vacuum tubes are amplification of a weak current, rectification of an alternating current (AC) to direct

electrochemical reaction: Mechanism of charge transfer: …view, this fast process of electron exchange between the electrode and a particle in solution is termed electron tunnelling through the energy barrier.

electron volt, unit of energy commonly used in atomic and nuclear physics, equal to the energy gained by an electron (a charged particle carrying unit electronic charge) when the electrical potential at the electron increases by one volt. The electron volt equals 1.602 × 10−12 erg, or 1.602 × 10−19

neutrino: … reported the discovery of the electron-antineutrino. In their experiments antineutrinos emitted in a nuclear reactor were allowed to react with protons to produce neutrons and positrons. The unique (and rare) energy signatures of the fates of these latter by-products provided the evidence for the existence of the electron-antineutrino.

nanotechnology: Top-down approach: Scanning beam techniques such as electron-beam lithography provide patterns down to about 20 nanometres. Here the pattern is written by sweeping a finely focused electron beam across the surface. Focused ion beams are also used for direct processing and patterning of wafers, although with somewhat less resolution than in electron-beam…

machine tool: Electron-beam machining (EBM): The EBM technique is used for cutting fine holes and slots in any material. In a vacuum chamber, a beam of high-velocity electrons is focused on a workpiece. The kinetic energy of the electrons, upon striking the workpiece, changes to heat, which vaporizes…

welding: Electron-beam welding: In electron-beam welding, the workpiece is bombarded with a dense stream of high-velocity electrons. The energy of these electrons is converted to heat upon impact. A beam-focusing device is included, and the workpiece is usually placed in an evacuated chamber to allow uninterrupted…

James Lovelock: … at NIMR, Lovelock invented the ECD, a device used in gas chromatography that draws upon the ionization properties of argon to detect trace atoms and molecules in a gas sample. The ECD has been used to determine the concentrations of halogen compounds in food and in the atmosphere, including compounds…

borane: Structure and bonding of boranes: …electrons, boranes are commonly called electron-deficient substances. Diborane(6) has the following structure:

ion-exchange resin: …the chelating resins and the electron-exchange resins. Chelating resins are styrene-divinylbenzene polymers to which iminodiacetate groups are introduced. This functional group forms complexes with all the metallic elements except the alkali metals, with stabilities that vary with the different metals; in analytical chemistry, they are used for the separation of…

materials science: Photovoltaics: The electron motion, and the movement of holes in the opposite direction, constitute an electric current. The force that drives electrons and holes through a circuit is created by the junction of two dissimilar semiconducting materials, one of which has a tendency to give up electrons…

magnetic resonance: Combined electron-spin and nuclear magnetic resonances: …is known as ENDOR (electron-nuclear double resonance), whereas driving an ESR to increase a nuclear magnetization, observed by NMR, is called DNP (dynamic nuclear polarization).

covalent bond, in chemistry, the interatomic linkage that results from the sharing of an electron pair between two atoms. The binding arises from the electrostatic attraction of their nuclei for the same electrons. A covalent bond forms when the bonded atoms have a lower total energy than that of

particle accelerator: Electron storage rings: Many storage rings have been constructed to study the interactions of electrons with positrons. The principal centres of this research are Cornell University; Stanford University; CERN; Tsukuba, Japan; Frascati, Italy; Beijing, China; and Novosibirsk, Russia.

antimatter: …and the process is called electron-positron creation, or pair production.

electron-probe microanalyzer, type of electron microscope used to provide chemical information. (A limitation of the conventional electron microscope is that it provides no elemental analysis.) Electron-probe microanalyzers have been developed since 1947 to carry out nondestructive elemental

particle accelerator: Electron-proton storage rings: The Hadron-Electron Ring Accelerator (HERA) at the DESY laboratory stores both electrons and protons. It is the only machine that operates in this way with particles of different masses. To do so requires two

electronegativity, in chemistry, the ability of an atom to attract to itself an electron pair shared with another atom in a chemical bond. The commonly used measure of the electronegativities of chemical elements is the electronegativity scale derived by Linus Pauling in 1932. In it the elements

ceramic composition and properties: Chemical bonds: This law of electroneutrality results in the formation of very specific stoichiometries—that is, specific ratios of cations to anions that maintain a net balance between positive and negative charge. In fact, anions are known to pack around cations, and cations around anions, in order to eliminate…

the Smiths: …New Order in the supergroup Electronic. Although Marr and Sumner had initially conceived their partnership to be temporary, the success of the 1989 single “Getting Away with It” inspired the pair to record three well-received dance albums. More than a decade after the demise of the Smiths, Marr formed his…

electronic adventure game: Action-adventure games: The first action-adventure game, Atari, Inc.’s Adventure (1979), loosely based on Crowther’s text-based game, was released for the Atari 2600 home video console. The game used a top-down view and allowed players to carry and use items without inputting text commands.

radiation: Molecular activation: Of special importance is electronic activation—i.e., production of an electronically excited state of the molecule (see Figure 1). This state can be reached (1) by direct excitation by photon absorption, (2) by impact of charged particles, either directly or indirectly through charge neutralization, or by excitation transfer from excited…

electronic adventure game, electronic game genre characterized by exploring, puzzle solving, narrative interactions with game characters, and, for action-adventure games, running, jumping, climbing, fighting, and other intense action sequences. Many modern electronic games, such as role playing

electronic artificial life game, electronic game genre in which players nurture or control artificial life (A-life) forms. One of the earliest examples is The Game of Life, a cellular automaton created by the English mathematician John Conway in the 1960s. Following a few simple rules, various

Electronic Arts (EA), American developer and manufacturer of video games for personal computers (PCs), video game consoles, and mobile devices. Established in 1982 by William M. (“Trip”) Hawkins, Electronic Arts (EA) has a product line that includes the popular franchises The Sims, EA SPORTS FC,

Coulomb’s law, mathematical description of the electric force between charged objects. Formulated by the 18th-century French physicist Charles-Augustin de Coulomb, it is analogous to Isaac Newton’s law of gravity. Both gravitational and electric forces decrease with the square of the distance

balance: …late 20th century were usually electronic and far more accurate than mechanical balances. A scanner measured the displacement of the pan holding the object to be weighed and, by means of an amplifier and possibly a computer, caused a current to be generated that returned the pan to its zero…

Electronic banking is the use of computers, phones, and other technologies to facilitate banking transactions rather than through human interaction. Electronic banking includes features like electronic funds transfer (EFT) and mobile payments for retail purchases, automatic teller machines (ATMs),

e-book, digital file containing a body of text and images suitable for distributing electronically and displaying on-screen in a manner similar to a printed book. E-books can be created by converting a printer’s source files to formats optimized for easy downloading and on-screen reading, or they

bulletin-board system (BBS), computerized system used to exchange public messages or files. A BBS was typically reached by using a dial-up modem. Most were dedicated to a special interest, which was often an extremely narrow topic. Any user could “post” messages (so that they appear on the site for

electronic carillon, 20th-century musical instrument in which the acoustical tone source—metal tubes, rods, or bars struck by hammers—is picked up electromagnetically or electrostatically and converted into electrical vibrations that are highly amplified and fed into loudspeakers placed in a belfry

information system: Securing information: For example, a payment in electronic cash is a type of message, with encryption used to ensure the purchaser’s anonymity, that acts like physical cash.

electronic carillon, 20th-century musical instrument in which the acoustical tone source—metal tubes, rods, or bars struck by hammers—is picked up electromagnetically or electrostatically and converted into electrical vibrations that are highly amplified and fed into loudspeakers placed in a belfry

e-cigarette, battery-operated device modeled after regular cigarettes. The e-cigarette was invented in 2003 by Chinese pharmacist Hon Lik, who initially developed the device to serve as an alternative to conventional smoking. In addition to the battery component, an e-cigarette comprises an

e-commerce, maintaining relationships and conducting business transactions that include selling information, services, and goods by means of computer telecommunications networks. Although in the vernacular e-commerce usually refers only to the trading of goods and services over the Internet,

telecommunication, science and practice of transmitting information by electromagnetic means. Modern telecommunication centres on the problems involved in transmitting large volumes of information over long distances without damaging loss due to noise and interference. The basic components of a

stock exchange: …Internet and the proliferation of electronic communications networks (ECNs) had allowed electronic trading, or e-trading, to alter the investment world. These computerized ECNs made it possible to match the orders of buyers and sellers of securities without the intervention of specialists or market makers. In a traditional full-service or discount…

band theory: In metals, forbidden bands do not occur in the energy range of the most energetic (outermost) electrons. Accordingly, metals are good electrical conductors. Insulators have wide forbidden energy gaps that can be crossed only by an electron having an energy of several electron volts. Because electrons…

electronic configuration, the arrangement of electrons in orbitals around an atomic nucleus. The electronic configuration of an atom in the quantum-mechanical model is stated by listing the occupied orbitals, in order of filling, with the number of electrons in each orbital indicated by

electronic warfare: …falls under the category of electronic countermeasures (ECM), and eavesdropping on enemy communications, which is known as signals intelligence (SIGINT) gathering. The purpose of jamming is to limit an enemy’s ability to exchange information by overriding radio transmissions or by sending signals to prevent radar detection or convey false information.…

electronic dance music, umbrella term for a panoply of musical styles that emerged in the mid-1980s. Rather than designating a single genre, electronic dance music (EDM) encompasses styles ranging from beatless ambient music to 200-beats-per-minute hardcore, with house music, techno, drum and bass,

Ross Perot: …and formed his own company, Electronic Data Systems (EDS), to design, install, and operate computer data-processing systems for clients on a contractual basis. EDS grew by processing medical claims for Blue Cross and other large insurance companies, and in 1968 Perot took the firm public in a shrewdly managed share…

Ross Perot: …and formed his own company, Electronic Data Systems (EDS), to design, install, and operate computer data-processing systems for clients on a contractual basis. EDS grew by processing medical claims for Blue Cross and other large insurance companies, and in 1968 Perot took the firm public in a shrewdly managed share…

database, any collection of data, or information, that is specially organized for rapid search and retrieval by a computer. Databases are structured to facilitate the storage, retrieval, modification, and deletion of data in conjunction with various data-processing operations. A database management

EDSAC, the first full-size stored-program computer, built at the University of Cambridge, Eng., by Maurice Wilkes and others to provide a formal computing service for users. EDSAC was built according to the von Neumann machine principles enunciated by the Hungarian American scientist John von

e-democracy, the use of information and communication technologies to enhance and in some accounts replace representative democracy. Theorists of e-democracy differ, but most share the belief that some of the traditional limits to citizenship in contemporary liberal-democratic polities—problems of

airport: Airport security: …concealed in clothing, and massive electronic detection systems (EDS), which can detect trace molecules released by explosive materials. The massive weight of EDS equipment frequently requires structural modifications to existing buildings, and the size of the equipment often requires a reallocation of floor space. In many airports, installed security equipment…

electronics: …effects of electrons and with electronic devices.

differentiator: There are also electronic differentiators, or electrical differentiating circuits. The Figure shows a differentiator based on an electrical analog. For a time-varying input, if the capacitive reactance XC shown in the schematic diagram is very large compared with the resistance R, the current, and hence output voltage

digital computer: Development of the digital computer: …alterable memory was implemented in EDVAC (electronic discrete variable automatic computer).

virtual sit-in: Three groups in particular—Electronic Disturbance Theater, the Electrohippies (now Electrohippies Collective), and RTMark—were known for their “hactivism.” In 1998 Electronic Disturbance Theater held one of the first virtual sit-ins. The action was in solidarity with the Zapatista National Liberation Army (EZLN), a Mexican guerrilla group, and was directed…

electronic eavesdropping, the act of electronically intercepting conversations without the knowledge or consent of at least one of the participants. Historically, the most common form of electronic eavesdropping has been wiretapping, which monitors telephonic and telegraphic communication. It is

encyclopaedia: Electronic encyclopaedias: Given the rapid pace of technological advancement in the contemporary world, it was to be expected that encyclopaedia publishers would seek ways to exploit new technologies in the field of information storage, retrieval, and distribution. During the 1960s and ’70s these new technologies…

spectroscopy: Electronic energy states: Unlike the atom where the system is centrosymmetric (see above Basic atomic structure), the energy relationships among the nuclei and electrons in a diatomic molecule are more complex and are difficult to characterize in an exact manner. One commonly

electronic fighting game, electronic game genre based on competitive matches between a player’s character and a character controlled by another player or the game. Such matches may strive for realism or include fantasy elements. The genre originated in Japanese video arcades and continues primarily

technology of photography: Electronic flash: The most common flash system depends on a high-voltage discharge through a gas-filled tube. A capacitor charged to several hundred volts (by a step-up circuit from low-voltage batteries or from the line voltage supply) provides the discharge energy. A low-voltage circuit generating a…

Electronic Frontier Foundation (EFF), nonprofit organization established to raise funds for lobbying, litigation, and education about civil liberties on the Internet. The Electronic Frontier Foundation (EFF) was founded in 1990 by American author and activist John Perry Barlow and American

money: Electronic money: First, depositors can use electronic funds transfers (EFTs) to withdraw currency from their accounts using automated teller machines (ATMs). In this way an ATM withdrawal works like a debit card. ATMs also allow users to deposit checks into their accounts or repay bank loans. While they do not replace…

electronic game, any interactive game operated by computer circuitry. The machines, or “platforms,” on which electronic games are played include general-purpose shared and personal computers, arcade consoles, video consoles connected to home television sets, handheld game machines, mobile devices

electronic fighting game: Home console games: Two reasons for the decline of arcades in the 1990s were the steep learning curve for newcomers to the fighting games and the increasing power of home video consoles. As the 16-bit home consoles, such as the Sega Genesis (1988) and the Super…

e-government, the use of information and communication technologies, particularly the Internet, in government. A popular way of conceptualizing e-government is to distinguish between three spheres of technologically mediated interactions. Government-to-government interactions are concerned with the

electronic health record (EHR), computer- and telecommunication-based system capable of housing and sharing patient health information, including data on patient history, medications, test results, and demographics. The technical infrastructure of electronic health records (EHRs) varies according

electronic instrument, any musical instrument that produces or modifies sounds by electric, and usually electronic, means. The electronic element in such music is determined by the composer, and the sounds themselves are made or changed electronically. Instruments such as the electric guitar that

chromatography: Chromatography–mass spectrometry methods: Modern electronic integrators will, when properly instructed, ignore electronic noise, compensate for baseline drift, start integration when a peak appears, integrate, and stop the process when the peak exits the detector. Integration, a process of summation, is accomplished by opening and closing a narrow electronic window,…

George Lucas: Early life and work: …films, including the futuristic parable Electronic Labyrinth THX 1138 4EB, which took first prize at the National Student Film Festival in 1965.

log: In the electronic log, which also protrudes through the bottom of the ship, a water-driven rotor turns a small electric generator, the current from which is proportional to the speed of the ship. This current is similarly used to produce a speed measurement.

e-mail, messages transmitted and received by digital computers through a network. An e-mail system allows computer users on a network to send text, graphics, sounds, and animated images to other users. The "at sign" (@) in the middle of an email address, separating the name of the emailer from the

postal system: Great Britain: An electronic mail system enables data for large mailings to be transmitted to local centres for enveloping and delivery.

electronic management game, electronic game genre in which players run a business or an enterprise. Unlike most electronic games, management games did not get their start in the arcades. With its characteristic requirement for slow meticulous planning, the genre first appeared for early home

prison: Other penalties: Finally, new technologies, such as electronic monitoring through ankle bracelets and other surveillance devices, have allowed probation and parole officers to restrict the movement of offenders who live in their own homes or in supervised accommodations.

electronic music, any music involving electronic processing, such as recording and editing on tape, and whose reproduction involves the use of loudspeakers. Although any music produced or modified by electrical, electromechanical, or electronic means can be called electronic music, it is more

ENIAC, the first programmable general-purpose electronic digital computer, built during World War II by the United States. American physicist John Mauchly, American engineer J. Presper Eckert, Jr., and their colleagues at the Moore School of Electrical Engineering at the University of Pennsylvania

electronic organ, keyboard musical instrument in which tone is generated by electronic circuits and radiated by loudspeaker. This instrument, which emerged in the early 20th century, was designed as an economical and compact substitute for the much larger and more complex pipe organ. The electronic

microwave oven, appliance that cooks food by means of high-frequency electromagnetic waves called microwaves. A microwave oven is a relatively small, boxlike oven that raises the temperature of food by subjecting it to a high-frequency electromagnetic field. The microwaves are absorbed by water,

PARC: PARC today: …the most interesting innovations was electronic paper, a flexible, reusable plastic material containing millions of charged bichromal beads suspended in individual oil-filled cavities. As designed by inventor Nick Sheridon, each bead could be oriented individually by an electric field to reproduce text or images. In addition to the advantages inherent…

television: Video recording: The recording of video signals on magnetic tape was a major technological accomplishment, first implemented during the 1950s in professional machines for use in television studios and later (by the 1970s) in videocassette recorders (VCRs) for use in homes. The home…

printing: Electronic phototypesetters: In phototypesetters of the third generation, the beam of light is replaced by a flow of electrons, which offers the advantage that the electrons can be deflected by means of magnetic fields without the intervention of mechanical parts such as mirrors and lenses.…

electronic platform game, electronic game genre characterized by maneuvering a character from platform to platform by jumping, climbing, and swinging in order to reach some final destination. The first genuine platform game was Nintendo Company Ltd.’s Donkey Kong (1981), an arcade game in which

electric polarization, slight relative shift of positive and negative electric charge in opposite directions within an insulator, or dielectric, induced by an external electric field. Polarization occurs when an electric field distorts the negative cloud of electrons around positive atomic nuclei

electronic product environmental assessment tool (EPEAT), online evaluation and procurement tool that helps consumers select environmentally friendly electronic products. It sets environmental criteria for examining desktop computers, laptops, computer monitors, printers, workstations, thin

Internet: Electronic publishing: The Internet has become an invaluable and discipline-transforming environment for scientists and scholars. In 2004 Google began digitizing public-domain and out-of-print materials from several cooperating libraries in North America and Europe, such as the University of Michigan library, which made some seven million…

electronic puzzle game, electronic game genre, typically involving the use of logic, pattern recognition, or deduction. Most popular puzzle games were made for personal computers, though some of them have been adapted for play on portable gaming systems and mobile telephones. Important games in

e-book: How e-books are read: …computers and game consoles, dedicated e-readers, mobile phones (especially powerful smartphones), and consoles attached to televisions or other screens. Rapid changes and advances in screen technology, processing power, the miniaturization of computing components, and wireless Internet connectivity are constantly changing the nature and range of e-reading devices.

electronic records, evidence, in digital form, of transactions undertaken by individuals or by organizations. At first glance, electronic records may seem to differ only in their physical medium from paper records. But the creation of records in electronic form has created practical, legal, and